I have the a Daisy Powerline Pellet Gun Rifle .22 caliber. It's the model from around the 1980's, needs fixin?

It was my dad's and the air pump inside it doesn't work. I took a shop they said send it to daisy for 40$ they'll do it. No way. It just releases air instead of holding it to push out the BB/Pellet. What parts do I need to fix it and how can I go about fixing it. Thanks! HELP